How Bad Is Past-Date Medicine?

As I recall there was a piece on PBS that told of the Army testing meds that were nearly 20 years old. That they were still at least 70% effective.

This is a common question of significant relevance for most of us. I personally have used many "expired" medications without apparent harm and have seen little documented evidence that this is harmful.
The one exception that is well documented and which I am sure your a familiar with is tetracycline which can have significant toxic effects if expired.

Hi, For solid dosage forms, they just let them sit on a shelf at std room temp and test them for 1.2.3.4.5 years. If you keep them cool, dry and dark, the stability may exceed your lifetime.

There are no equations for room temperature stability of solid dosage forms. The original formular of tetracycline contained the cheap excipient citric acid that caused the instability and toxicity for TCN. That has since been corrected.

For liquid dosage forms, there is the infamous Ahrrenius Plot ie log K verses log 1/T in degrees kelvin that is correct if it works and is called an erroneous polt if it dosen't work. The FDA allows a 1 year stability for dispensed drugs or the bottle stability date which ever is shorter. I hope the info helps.

I my self have used out of date drugs, with no ill effects. The drugs; (methocarbimol, carisoprodol) muscle relaxants, provental inhalers, 2001' Neurontin (gen name gabepentin) according to my VA doctor, originally prescribed for seizures, was found to be effective for involuntary nerve related muscle twitches and cramps.

I suffer from a 1985 military service related disability resulting in degenerative shoulder, neck and back conditions, now causing pinched nerves. Surgery is pending.

Interesting so for the most part medication is not toxic just ineffective?

That's a relief I just took 4 poofs from a salbutomol inhaler that was out of date. Only realized after I checked the date. It was out of date by a year. Eeek!!!

But no ill effects so far:-)))